1. Technical Field
The present invention relates to a shear structure, more particularly to a tree shear for cutting a branch of a plant.
2. Description of Related Art
A tree shear is used to cut a branch of a plant. Operating the tree shear usually requires a larger force, so the tree shear includes longer handles as arms of force to achieve an objective of saving force. There are many commercially available tree shears which each has handles with adjustable lengths, most of their ways of adjusting the lengths of the handles are different, but their adjustment concepts usually involve extendable pipe structures and a controlling device to fasten lengths of the pipes.
However, when the tree shear is opened, longer handles may cause an excessive opening degree and the user must open hands greatly to operate the tree shear. Longer handles can provide a force-saving effect, but the handles with the excessive large opening degree are non-ergonomic and hard to operate opening and closing actions for cutting. In addition, the controlling device for adjusting the lengths of the handles cannot be controlled during cutting operation, so it is not convenient to use a conventional tree shear.